As a mechanism for performing a focus adjustment or a zoom adjustment in such a spotlight, there is a mechanism which a first lens and a second lens provided in a lens barrel of the lamp body are supported along the optical axis by a first lens holder and a second lens holder so as to be slid forward and backward, respectively, a first adjustment handle and a second adjustment handle each corresponding to the lens holder are arranged at the outside of the lens barrel so as to be slid forward and backward, each of the adjustment handles is slid to separately adjust the position of each lens so that the distance between the lenses is adjusted to adjust the size of the projected image (zoom adjustment) and the distance between the light source and each of the lenses is adjusted to perform the focus adjustment of the transmitted light (for example, see Japanese unexamined Utility Model Publication No. 62-89708).
However, performing the zoom adjustment and the focus adjustment by separately sliding each lens by the operation of the adjustment handle provided in each lens needs experience and intuition for the handle operation. Accordingly, there is a problem in that, if a user is not an expert, it is difficult to perform the above-mentioned adjustments and the operations thereof must be repeatedly performed.
In order to solve the above-mentioned problem, a technique for adjusting the distance between two lenses by rotating one handle to adjust the size of the projected image, and adjusting the distance between the light source and each of the lenses by sliding the handle to perform the focus adjustment of the transmitted light has been suggested (for example, see U.S. Pat. No. 6,092,914).